Blends of polyphenylene ether resins and polyamide resins offer desirable properties such as impact strength and chemical resistance and are useful in many thermoplastic applications. Several patents and applications have provided blends of these materials in various proportions. U.S. Pat. No. 3,379,792 by Finholt provided compatible polyphenylene ether-polyamide compositions. Other patents have utilized various compatibilizing agents to improve the properties of the blend.
The co-pending applications mentioned above provide improved polyphenylene ether-polyamide compositions by inclusion of certain effective compatibilizing agents. In Ser. No. 663,745 the inventors discovered a functionalized polyphenylene ether composition which could compatibilize a polyphenylene ether-polyamide composition as shown in the 654,922 application. In a typical example from those patent applications, a polyphenylene ether molecule is functionalized with a compound such as trimellitic anhydride acid chloride (TAAC) which thereby provides a TAAC-functional polyphenylene ether. It was discovered that this TAAC-functional polyphenylene ether was itself a very effective compatibilizer for polyphenylene ether-polyamide blends. It was discovered that the TAAC-functional polyphenylene ether compound could replace all or part of the conventional polyphenylene ether resin in such polyphenylene ether-polyamide compositions.
It has now been discovered that it is possible to bypass the step of separately functionalizing the polyphenylene ether in order to provide an effective compatibilizing agent. The compatibilizing agent (such as trimellitic anhydride acid chloride) can be incorporated directly in a polyphenylene ether-polyamide resin composition and effect useful compatibilization therein under certain conditions. This offers the important advantage of elimination a processing step, thus offering greater flexibility in the manufacturing processes.